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xRuby

xRuby is a Ruby to Java compiler which compiles Ruby source code (.rb) to Java bytecode (.class).

JRuby

JRuby is the effort to recreate the Ruby interpreter in Java. Currently, the interpreter is written in C. The Java version will be tightly integrated with Java to allow both to script any Java class and to embed the interpreter into any Java application.

orzjisp

orzjisp is a variant of orzlisp on JVM which is a variant of LISP on RubyVM.

Java+

Java++ is a Java+ preprocessor that supports multi-line strings with executable inclusions in Java+ as in Perl, Ruby, and Python.